1. Field of the Invention.
The present invention relates generally to improved nautical clock apparatus and methods, and more particularly, to improved nautical clock apparatus which, among other things, indicate states of tides and methods of improving such tide state indication.
2. Description of the Prior Art
Nautical clocks which continuously indicate the states of ocean tides have heretofore been developed and utilized. Such clocks can also indicate the phases of the moon and are usually combined with conventional time of day clocks.
Ocean tides are primarily caused by the gravitational forces exerted on the earth by the moon and the sun with the moon's gravitational force being dominate. Based on the 24 hour and 50.47 minute time in a lunar day, i.e., the average time between moon rise to moon rise on two consecutive nights, there is a high tide approximately every 12 hours and 25.235 minutes. A low tide typically follows every high tide by about 6 hours and 12.618 minutes.
Prior nautical clocks which have included tide state indicators have been based on the time interval of about 12 hours and 25 minutes between high tides. However, because of a variety of factors such as the relative locations of the moon and the sun with respect to the earth, the inclinations of the orbits of the sun and the moon with respect to the orbit of the earth and other celestial perturbations, the time between high tides varies continuously. As a result, nautical clocks utilized prior to the present invention have generally provided only rough indications of the times of high and low tides.
Thus, there is a need for an improved nautical clock for indicating the state of the tide which is more accurate than the clocks used heretofore. Also, there is a need for an improved nautical clock which accurately indicates the state of the tide and also indicates the phase of the moon and the time of day.